Various web or sheet formed products manufactured on a continuous basis either often are heated during processing, or are subjected to the application of heated materials, so as to necessitate cooling of the web during its travel through the processing line. For example, roofing materials, such as asphalt shingles, commonly are produced in a process line in which a web of sheet material, made of organic or fiberglass material, is drawn from a supply roll through (1) a coating station in which the web is coated with a hot liquid tar or asphalt, (2) a surfacing station in which granular surface material is directed onto the hot liquid coating, (3) a cooling and press roll station in which the granular surface material is pressed into the hot liquid coating and the sheet material and coating are cooled by spraying a cooling liquid, such as water, onto the moving sheet material, and (4) cutting and stacking stations in which the cooled sheet material is cut into predetermined-size shingles and stacked. Inconsistencies in processing conditions can significantly affect the quality of the finished shingle product.
Cooling the moving sheet material and hot liquid coating at the cooling station in such asphalt production lines has been particularly problem prone. Unevenness in cooling of the sheet material can significantly affect the quality and consistency of the resulting product, and particularly the extent of granular penetration and retention in the coating. Inadequate or excessive cooling of the web entering the cutting and subsequent stacking stations also can cause jamming, production interruption and rejected product. Heretofore, systems for cooling such web based products typically use manually controlled spray headers in the form of a pipe which positions a plurality of coolant directing spray nozzles across the width of the moving web. For a variety of reasons, in such cooling systems the temperature across the width of the moving web cannot be uniformly maintained. Since the headers are a fixed distance from the web, as the liquid spray pressure is varied for controlling cooling, the angle of the discharging spray can change considerably during processing. At lower pressures, a narrow spray angle can result in portions of the web being missed by the spray, while at higher pressures wider spray angles can create overlapping spray patterns. In each case, uneven cooling can occur across the width of the web.
When webs of different widths are processed in the same line it is even more difficult to uniformly cool the web across the width of the sheet material without major re-setup of the processing line. Non-uniformity in cooling also can occur by reason of the surrounding ambient conditions, such as if a door or window is open along one side of the processing line. Clogging of nozzles in the header further can result in significant temperature variations across the width of the moving web. To ensure sufficient cooling, operators typically error on directing excess cooling liquid, which results in costly waste and requires handling of the excessively applied liquid. Moreover, since the liquid spray headers typically are manually operated, following a shift changeover to a new operator, the character and quality of the finished product can vary significantly.